膨胀石墨和碳纳米管涂层对相变材料性能的影响

A low-cost and user friendly method for adding coatings is proposed to address the current issue of relatively complex and costly preparation of composite phase change materials for photothermal conversion and storage. The expanded graphite and carbon nanotubes were used for improving the solar thermal conversion and storage performance of paraffin wax/expand perlite composite. The effect of different mass ratios of expanded graphite and carbon nanotubes on solar thermal conversion and storage at varying solar intensities was investigated. The results of the solar-thermal experiment indicated that the thermal energy storage rate of the pure paraffin wax and paraffin wax/expand perlite could be improved by adding expanded graphite. In comparison with pure paraffin wax and paraffin wax/expand perlite, the heat energy storage rate of composites with expanded graphite content was improved two times and 0. 63 times, respectively. The addition of carbon nanotubes coating could effectively improve solar thermal performance. The photothermal conversion efficiencies for paraffin wax and paraffin wax/expand perlite were improved by a factor of 1. 82 and 0. 6, respectively. With the cycle time increasing, the photothermal converting property of the composite declined and maintained steady after a certain cycle. The steady maximum temperature was about 65 °C. The photothermal conversion efficiency of most of the studied samples was below 90%, and the photothermal conversion efficiency of this study could reach 90. 76%. Therefore, the addition of carbon nanotubes to the surface of composite phase change materials has been demonstrated as a simple and effective strategy to improve the photothermal conversion performance.